This invention relates to a novel process for preparing a .beta.-lactam derivative useful as a synthetic intermediate of a .beta.-lactam type antibacterial agent having an antibacterial activity, and relates to a synthetic intermediate of said .beta.-lactam derivative.
As a .beta.-lactam type antibacterial agent, there have been known various compounds including a penem or carbapenem series compound such as thienamycin and imipenem, and a cephem, carbacephem or oxacephem series compound such as cephalexin.
As to processes for synthesizing these compounds, there have been known, for example, a process which proceeds through an intermediate having diphenylphosphoryloxy group at 2-position of a carbapenem skeleton described in Japanese Provisional Patent Publication No. 123182/1982 as a process for synthesizing a carbapenem (or penem) series compound, a process which proceeds through an intermediate having methanesulfonyloxy group at 3-position of a cephem skeleton described in Japanese Provisional Patent Publication No. 21685/1992 as a process for synthesizing a cephem series compound, and others. However, the conventional processes have problems to be cancelled such as many operation steps and complicated reaction operations. Thus, it has been demanded to develop a process which can prepare a desired antibacterial agent more efficiently.